Diesel engines may include various components to control a variety of atmospheric emissions produced by the engine. For example, diesel engines may include a diesel particulate filter to trap soot and other particulate matter emitted by the engine.
Various approaches have been used to determine an amount of soot emissions in an engine's exhaust. For example, models may be used to estimate amounts of particulate matter produced in real-time. Alternatively, soot sensors, such as soot sensors including an aluminum oxide ceramic for measuring particulate matter, may be used. However, model accuracy may be sufficiently degraded to provide high enough resolution for soot emission determination. Likewise, available soot sensor may have insufficient sensitivity and response times.
The inventors herein have realized that accurate particulate matter information for controlling processes and parameters may be realized by a method for operating an engine comprising correlating a measured property associated with a carbon nanostructure layer to an amount of particulate matter from an exhaust stream of the engine, wherein the carbon nanostructure includes a plurality of carbon nanostructures, and adjusting engine operation based on the amount of particulate matter.
For example, the inventors have recognized that a soot sensor including a carbonaceous material rather than a ceramic substrate may facilitate higher sensitivity and faster response times for measuring carbonaceous particulate matter. Even further, carbon nanostructures may be functionalized to facilitate sensitivity to a plurality of constituents in the exhaust stream of the engine. In this way, it may be possible to facilitate more appropriately timed and more accurately controlled regeneration of a diesel particulate filter.